1. Field of the Invention
This invention relates to ice condenser containments employed for condensing steam generated from the primary water of a nuclear reactor in the invent of an accidental loss of coolant and, more particularly, to a method and apparatus for servicing such ice condenser containments to permit replacing ice which has sublimated and thus been lost from within the ice condenser containment.
2. State of the Prior Art
Ice condenser containments, also known as ice baskets, are employed with nuclear reactors for condensing the steam from the primary water of the reactor in the event of an accidental loss of coolant. In a typical installation, there are provided approximately 2,000 ice baskets, each of which is approximately one foot in diameter and 50 feet in height and is filled with approximately 1,500 pounds of ice. The sidewalls of the ice basket, substantially cylindrical in configuration, are perforated to permit rapid exposure of the steam to the ice and corresponding, rapid cooling.
A problem has developed in the use of such ice condenser containments, in that due to sublimation of the ice, the initial volume and weight decreases with time and thus the ice must be replenished, or replaced. A minimum required amount of ice is typically at least 1,200 pounds for each ice basket, for assuring its effectiveness for counteracting the accidental loss of coolant, as above referenced.
FIG. 1 is an elevational cross-sectional view of an individual ice basket 10; as before noted, the ice basket 10 is of generally cylindrical configuration, approximately 50 feet in height and approximately one foot in diameter. Cruciforms 14 are positioned at approximately six foot height spacings along the axial height of the basket 10 and comprise metal straps approximately 1/8 inch thick and typically 11/2 inches in height extending diametrically across the interior of the basket 10 and welded at the ends thereof to the interior sidewalls of the basket 10. Typically, each cruciform comprises two such diametrically extending straps suitably, integrally joined at the intersections thereof along the axis of the basket 10, and thus in an "X"-shaped configuration. The cruciforms were intially provided to afford increased lateral support for the ice basket 10 as a precaution against severe seismic disturbances; it has been determined that such welded-in-place cruciforms are not necessary to maintaining adequate lateral support and that alternative structures instead may be employed.
The cruciforms, however, have imposed a substantial obstacle to replenishing the supply of ice, as the latter is depleted due to sublimation. For example, as seen in FIG. 1, the successively lower compartments contain inadequate charges of ice due to sublimation loss, and remain spaced apart due to the presence of cruciforms 14. Thus, while access may be had to the upper, open end of the ice basket 10 for recharging the first and possibly the second upper compartments, the lower compartments are inaccessible and contain an inadequate charge of ice. The ice basket thus loses its required cooling capability, presenting a potentially serious deficiency in its required coolant capacity.